This book presents recent developments in the theory of gearing and the modifications in gear geometry necessary to improve the conditions of meshing. Highlighted are low-noise gear drives that have a stable contact during meshing and a predesigned parabolic transmission error function that can handle misalignment during operation without sacrificing the low-noise aspects of operation. This book also provides a comprehensive history of the development of the theory of gearing through biographies of major contributors to this field. The author's unique historical perspective was achieved by assiduous research into the lives of courageous, talented, and creative men who made significant contributions to the field of gearing.